In charged particle beam microscopy (e.g., scanning electron microscopy) a probe beam of charged particles probes a target surface. Secondary particles are generated by interaction between the probe beam and the surface. The secondary particles may be detected and an image may be generated based on detection of the secondary particles. The images are typically built up in the form of pixels, wherein a pixel value in the image, e.g. a grey scale, is related to the intensity of secondary particles at a corresponding location on the target surface. In the prior art, the resolution of charged particle beam microscope images has been partly dependent on the stability of the surface being probed. Most imaging techniques rely to some degree or another on the assumption that the target does not move relative to the probe beam in a plane parallel to the surface. In practice, some degree of vibration of the target surface may be present. For low resolution images, i.e., images having pixel spacing greater than the amplitude of vibration of the target, the vibration amplitude is typically small enough that it does not significantly affect the image. However, resolution may be detrimentally affected if the pixel spacing is comparable to the vibration amplitude.
The field of view of a charged particle microscopy system may be limited. In order to obtain images covering an entire target surface it is often necessary to move the target in order to image different locations on the surface. Such movement of the target may induce vibration of the surface. To overcome the effects of target vibration, modern charged particle microscopy systems often make use of complex and expensive vibration damping for the stage that holds the target. Such damping can significantly increase the cost of a microscopy system. In addition, damping equipment often requires a period of time for vibration of the stage to settle out following movement of the target between images. This settling time reduces the rate at which images of a target can be acquired and decreases the throughput of the charged particle microscope system.
It is within this context that embodiments of the present invention arise.